Shindawa Trimmer C4 Hybrid Technology

[boraticus]

Good info Cujet.

I've plenty of experience with two stroke engines. I own six older two stroke motorcycles, ten or so modern two stroke OPE engines as well as a two stroke snowmobile and four two stroke outboard engines. So, no shortage of two stroke knowledge here.

I also participate in a couple of two stroke specific forums to draw on the experience/knowledge of a number of very well known and respected persons who were prominent in motorcycle racing back in the sixties and seventies when two strokes were king. They all make the same statement: More oil = more power and reliability. Anyone claiming otherwise is talking through their hat...

 

[Pablo]

Originally Posted By: scudpilot
I just talked to a friend of mine and he was telling me that he just burned up one of the new technology Hybrid motors, which is a 4stroke engine, but uses oil/gas mixture with no crankcase. Manufacturer recommends normal oil at 50:1.
This trimmer is a Shindawa C4 Hybrid. He was using Amsoil Sabre professional at 80:1 like he uses in all his other commercial machines. Never had a problem and loves the Amsoil convenience. He owns a landscaping company.
Has anyone here had any experience with these motors?


Did he ever find the root cause of the failure?

What type of oil does his manual say to use? JASO FD, correct?
Amsoil Saber Pro Mix 100:1 meets JASO FD. 80:1 should have been plenty of oil.

I understand the concept of more oil makes more power to a point, but less oil does have a purpose, and that is lower emissions.

 

[scudpilot]

No. He just told me that the insides were "dry" when he opened the engine up. He is a car mechanic by trade so I believe he knows the internals of an engine. He can't get replacement parts for the two trimmers so he is just replacing them with 2 stroke trimmers. Interesting part is that the backpack blower he is using with the same technology is still running great.
I truly suspect that his guys put straight gas in them and were afraid to tell him. I guess we will never know.
He wants to start running all his 2 stroke machines at 50:1 now. I explained to him that I have used the Sabre Professional at 80:1 in a lot of machines of every type with no problems, but he insists.
And yes JASO FD at 50:1.

 

[boraticus]

I'd be willing to bet that using 50:1 will increase over all engine life.

Don't forget that the only lube the crank/cylinder sees is that pittance of oil coming in with the fuel. I'd suspect that the reason more oil equals more power is for friction reduction.

 

[Mamala Bay]

Originally Posted By: scudpilot
No. He just told me that the insides were "dry" when he opened the engine up. He is a car mechanic by trade so I believe he knows the internals of an engine. He can't get replacement parts for the two trimmers so he is just replacing them with 2 stroke trimmers. Interesting part is that the backpack blower he is using with the same technology is still running great.
I truly suspect that his guys put straight gas in them and were afraid to tell him. I guess we will never know.
He wants to start running all his 2 stroke machines at 50:1 now. I explained to him that I have used the Sabre Professional at 80:1 in a lot of machines of every type with no problems, but he insists.
And yes JASO FD at 50:1.


The stronger color of the dye in 2 cycle oil does help. When you put lean mixture or the 2 cycle oil has a weak dye it's hard to tell from straight gas and 2 cycle oil mixture. Human error occurs and it can be costly resulting in burned engines.

 

[Cmarti]

FWIW

Interesting study over at Arborist.com showed the more oil in the ratio the hotter the chainsaw ran. Heat does not necessarily equal wear, but I found it interesting and the opposite of what I would have thought. The oil lubricates, but the fresh fuel load cools. The more gas in the load, the richer the load and the cooler it ran. The ratio was changed, but the carb settings were not. Although I have found temp and humidity affect the carb more than a reasonable fuel ratio. The ratios tested were 32:1/40:1/50:1.

 

[boraticus]

Originally Posted By: Cmarti
FWIW

Interesting study over at Arborist.com showed the more oil in the ratio the hotter the chainsaw ran. Heat does not necessarily equal wear, but I found it interesting and the opposite of what I would have thought. The oil lubricates, but the fresh fuel load cools. The more gas in the load, the richer the load and the cooler it ran. The ratio was changed, but the carb settings were not. Although I have found temp and humidity affect the carb more than a reasonable fuel ratio. The ratios tested were 32:1/40:1/50:1.


It's true that more heat in the combustion chamber will result because the oil is displacing fuel in the air/fuel mix causing a leaner condition. However, despite the increased combustion temps, the reciprocating parts within the engine are getting more lubrication. In effect, the heat isn't compromising engine operation and in addition to that, heat in the right place is a good thing.

It's a well known fact that the hotter the exhaust gas is, the better/quicker it will flow. Ever wonder why some people wrap the headers in a heat proof fabric? It's to keep the header hot.

However, the balancing act is to keep the heat in the header and not in the cylinder. I've modified the heads on my '74 RD350 by removing the squish band. All it took was shaving .020" - 030" from the surface of the heads, of which, most of it was the squish band. That very minor adjustment has sufficient effect to improve gas flow significantly enough to reduce the heat accumulation in the piston crown and engine head as well as expedite the hot gas to the expansion chamber.

Another important heat management factor is engine timing. These old bikes had static timing at 1.8 mm. before TDC which is roughly 23 to 24 degrees. Points wear and mis-adjustment can drastically effect this setting. More advance at higher rpms causes more heat to accumulate in critical components. Accordingly, having a means to adjust the ignition curve to retard it as engine rpms rise, will go a long way to move the heat from the cylinder to the expansion chamber. That's one of the reasons I installed a state of the art programable ignition systems on my RDs. I get more power, less heat build up in the engine and better exhaust flow.

These bikes have oil injection pumps, which increase oil flow as rpms rise. So, despite the fact that more oil is being introduced into the fuel at higher rpms, the steps I've taken will go a long way to keep the engine running at the desired temperatures.

 

[Cujet]

Originally Posted By: Cmarti
FWIW

Interesting study over at Arborist.com showed the more oil in the ratio the hotter the chainsaw ran. Heat does not necessarily equal wear, but I found it interesting and the opposite of what I would have thought. The oil lubricates, but the fresh fuel load cools. The more gas in the load, the richer the load and the cooler it ran. The ratio was changed, but the carb settings were not. Although I have found temp and humidity affect the carb more than a reasonable fuel ratio. The ratios tested were 32:1/40:1/50:1.


Interesting!

The testing we did was on water cooled engines. We made no attempt at measuring the heat load.